The fundamental question of how cells of bones and teeth assemble and mineralize their respective matrices in such a coordinated and superbly biofunctional way is still largely unanswered. The Protein Chemistry Unit has been performing a variety of experiments and collaborations to help determine the structure-function relationship of several of the more interesting noncollagenous proteins. Publications fall into four general categories. 1) Two closely related proteoglycans, decorin and biglycan, continued to be central to our interests. Advances have included work on the biglycan knock-out mouse, partial characterization of the human biglycan promoter as well as localization of the endocytosis domain of human decorin to Leu125-Val230. 2) Continued work on the gene structure of the enamel protein, tuftelin. 3) Advances in the understanding of McCune-Albright syndrome including data indicating that the disease directly affects the osteogenic lineage. Furthermore we have aided in the development of an implantation model of the disease. 4) Finally we have continued our exploration of the possible role of bone sialoprotein in osteotropic cancers. With our colleagues, we have shown that BSP is an interesting marker for breast, lung, thyroid and prostate cancers.